High Leptin Levels Linked to Decreased Depression

Leptin is a hormone released by adipocytes (fat cells) that signals satiety, or fullness, after a meal. Studies in obese people have found that there is a link between weight gain and an inability to produce adequate amounts of leptin. A separate study looks at a new role – high levels of the hormone may also reduce symptoms of depression.

Leptin Levels Influence a Variety of Body Processes

Elizabeth Lawson MD of Massachusetts General Hospital and Harvard Medical School and colleagues studied the relationship between leptin levels and symptoms of anxiety and depression in 64 women of different weights. Fifteen of the women had anorexia nervosa, an eating disorder characterized by abnormally low weight and body fat. Twelve were of normal weight but had hypothalamic amenorrhea, or the cessation of menstruation. Leptin is also known to play a role in regulation of reproductive function. Twenty of the remaining women were of normal weight and 17 were overweight or obese, but all in good health.

The study participants were asked questions to assess symptoms of depression and anxiety with higher scores indicating more symptoms. Blood leptin levels were measured and BMI was assessed.

The researchers found that higher leptin levels were linked to decreased symptoms of anxiety and depression, a relationship that was independent of BMI. The finding, also seen in animal studies, indicates that leptin may mediate symptoms of depression and that this effect is not a function of weight status, Dr. Lawson said.

Leptin injections are already being tested in animal models as an obesity treatment and further research in humans “will be important in understanding whether this hormone has a potential role in the treatment of depression,” concluded the authors.

It is interesting to note that a previous study conducted at the University of Florida found that exercise can have a positive effect on leptin levels, allowing the hormone to work properly in the body. Exercise has long been associated with a decrease in depression symptoms, a finding that could be relevant in future studies as well.

The results from the study are being presented during The Endocrine Society’s 93rd Annual Meeting this week in Boston.